server.js

var express = require("express");
const app = express()
var restRouter = require("./routes/rest");
var indexRouter = require("./routes/index");
var path = require('path');
var mongoose = require("mongoose");

// for socket, can not use express's app.listen, because it's used by main service
var http = require('http');
var socket_io = require('socket.io');
var io = socket_io();
var socketService = require("./services/socketService.js")(io);

// mongodb://<dbuser>:<dbpassword>@ds213259.mlab.com:13259/oj
// <dbuser> == user, <dbpassword> == user
mongoose.connect("mongodb://user:user@ds213259.mlab.com:13259/oj");

app.use(express.static(path.join(__dirname, '../public')));

app.use('/', indexRouter)

app.use("/api/v1", restRouter);

// handle refresh and direct webpage address other than '/'
app.use(function(req, res) {
  // send index.html to start client side
  res.sendFile("index.html", {
    root: path.join(__dirname, '../public/')
  });
});

var server = http.createServer(app);
io.attach(server);
server.listen(3000);

server.on('error', onError);
server.on('listening', onListening);

function onError(error) {
  throw error;
}

function onListening() {
  var addr = server.address();
  var bind = typeof addr == 'string'
    ? 'pipe ' + addr
    : 'port ' + addr.port;
  console.log('Listening on ' + bind);
}